JP7142821B2 - Adhesives and adhesive sheets - Google Patents

Description

TECHNICAL FIELD The present invention relates to an adhesive and an adhesive sheet.

BACKGROUND ART Conventionally, adhesive sheets having an adhesive layer formed on a base sheet have been widely used as surface protection sheets for various members. Examples of adhesives include acrylic adhesives, silicone adhesives, urethane adhesives, and the like. Acrylic pressure-sensitive adhesives are excellent in adhesive strength, but because of their high adhesive strength, they are not removable after they have been applied to adherends. Silicone pressure-sensitive adhesives tend to contaminate adherends, and the relatively low molecular weight silicone resin may volatilize and adhere to the surfaces of equipment such as electronic devices, causing problems. On the other hand, the urethane-based pressure-sensitive adhesive has good adhesion to the adherend, is relatively excellent in removability, and is difficult to volatilize.
In the present specification, unless otherwise specified, the "adhesive" is a removable adhesive (removable adhesive), and the "adhesive sheet" is a removable adhesive sheet (removable adhesive sheet ).

As a method for producing a urethane-based pressure-sensitive adhesive, there is a method using a hydroxyl group-terminated urethane prepolymer, which is a reaction product of an active hydrogen group-containing compound such as a polyol and a polyisocyanate, and a polyfunctional isocyanate compound, and a method using a hydroxyl group-terminated urethane prepolymer. There is also a method (one-shot method) in which the polyol and the polyfunctional isocyanate compound are reacted at once without any reaction.

A general adhesive sheet manufacturing method includes a coating step of applying an adhesive onto a base sheet, and a heat-drying treatment of the formed coating layer to form an adhesive layer containing a cured product of the adhesive. It includes a heating step, a winding step of winding the obtained adhesive sheet around a core to form an adhesive sheet roll, and a curing step of curing the adhesive sheet roll.

Flat panel displays such as liquid crystal displays (LCDs) and organic electroluminescent displays (OELDs), as well as touch panel displays that combine such flat panel displays with touch panels, are widely used in televisions (TVs), personal computers (PCs), mobile phones, and It is widely used in electronic devices such as personal digital assistants.
Urethane pressure-sensitive adhesive sheets are used for flat panel displays and touch panel displays, as well as substrates (glass substrates and ITO/glass substrates in which an ITO (indium tin oxide) film is formed on a glass substrate) that are manufactured or used in these manufacturing processes. etc.) and as a surface protection sheet for optical members and the like.

JP-A-11-256124 WO2015/141380 JP 2017-193601 A WO2015/141379

The urethane-based pressure-sensitive adhesive begins to harden immediately after it is manufactured. If the initial curability of the urethane-based pressure-sensitive adhesive is too low, the re-peelability of the pressure-sensitive adhesive layer is reduced, and the components of the pressure-sensitive adhesive layer tend to adhere to fingers, adherends, and the like in contact with the pressure-sensitive adhesive layer. In this case, so-called "adhesive residue" (also referred to as "adherend contamination") that remains of the adhesive layer components on the finger, adherend, etc., tends to occur after the adhesive sheet is peeled off from the finger, adherend, etc. . The urethane pressure-sensitive adhesive preferably has good initial curability.

When the pressure-sensitive adhesive sheet is exposed to a heat environment, especially a hot and humid environment, the anchoring property between the adherend and the pressure-sensitive adhesive layer increases, resulting in an increase in the pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer and a tendency to decrease removability. There is The pressure-sensitive adhesive sheet preferably has good removability even when exposed to a hot environment, particularly a hot and humid environment, and does not stain the adherend such that components of the adhesive layer remain on the surface of the adherend after re-peeling.

Patent Documents 1 to 4 are listed as related technologies of the present invention.
Patent Document 1 discloses an aqueous dispersion containing a polymer of a monomer whose main component is a (meth)acrylic acid alkyl ester having an alkyl group having 4 to 12 carbon atoms, and the polymer has a weight average molecular weight of 250. 10,000 or more and a removable water-dispersible pressure-sensitive adhesive (acrylic pressure-sensitive adhesive) having a molecular weight of 5,000,000 or less per polymer molecule of 5 or less (claim 1).

In Patent Document 2,
(A) obtained by copolymerizing a monomer component containing a (meth)acrylic acid alkyl ester having an alkyl group with 4 to 18 carbon atoms and a carboxyl group-containing monomer, and gel permeation chromatography/multi-angle laser light scattering detection; a (meth)acrylic copolymer having a degree of branching of 0.55 or less and an acid value of 0.1 to 7.8 mgKOH/g as measured by an instrument (GPC-MALS);
(B1) an isocyanate compound,
(B2) A pressure-sensitive adhesive composition for a polarizing plate (acrylic pressure-sensitive adhesive) containing a metal chelate compound is disclosed (claim 1).

Patent Document 3 discloses a photocurable pressure-sensitive adhesive precursor composition containing an ethylenically unsaturated monomer, a prepolymer having monomer units derived from a hydrogen-donating monomer, and a hydrogen-abstracting photoinitiator. (Claim 1).
The ethylenically unsaturated monomers are preferably (meth)acrylates (paragraph 0021).
The hydrogen-donating monomer preferably has an ethylenically unsaturated double bond and at least one selected from the group consisting of an amino group, an amide group, a hydroxyl group, a thiol group, a heterocyclic ring, and an alkylene oxide chain (claim 2).
Patent Document 3 discloses a photocurable pressure-sensitive adhesive containing a randomly branched (co)polymer having a branching degree of 0.25 or more and 0.44 or less (claim 5).
In Examples 1 to 3 of Patent Document 3, acrylic adhesives are produced.

In Patent Document 4, (A) is obtained by copolymerizing a (meth)acrylic acid alkyl ester having an alkyl group with 4 to 18 carbon atoms and a monomer component containing a hydroxyl group-containing monomer, and a gel permeation chromatography method/multiple A pressure-sensitive adhesive composition for a polarizing plate containing a (meth)acrylic copolymer having a branching degree of 0.55 or less as measured by an angular laser light scattering detector (GPC-MALS), and (B) an isocyanate compound. (acrylic adhesive) is disclosed (claim 1).
The code of each component described in Patent Documents 1 to 4 is the code described in these documents and has nothing to do with the code used for each component of the present invention.

Patent Documents 1 to 4 describe the number of branches or degree of branching of acrylic (co)polymers. All of these patent documents relate to acrylic pressure-sensitive adhesives, not to urethane-based pressure-sensitive adhesives. In urethane pressure-sensitive adhesives, there is no literature describing the degree of branching of prepolymers or raw materials thereof.

The present invention has been made in view of the above circumstances. An object of the present invention is to provide a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer, and a pressure-sensitive adhesive sheet using the same.

The pressure-sensitive adhesive of the present invention is
a hydroxyl group-terminated urethane prepolymer (UPH) which is a reaction product of one or more active hydrogen group-containing compounds (H) having a plurality of active hydrogen groups in one molecule and one or more polyisocyanates (N);
A pressure-sensitive adhesive containing a polyfunctional isocyanate compound (I),
A hydroxyl group-terminated urethane prepolymer (UPH) is a urethane pressure-sensitive adhesive having a branching degree of 0.2 to 0.8 as measured by the GPC-MALS method.

In the adhesive of the first embodiment according to the present invention,
One or more active hydrogen group-containing compounds (H) contain 50% by mass or more of active hydrogen group-containing compounds (HX) having a branching degree of 0.5 or less as measured by GPC-MALS,
The hydroxyl group-terminated urethane prepolymer (UPH) has a branching degree of 0.2 to 0.6 as measured by the GPC-MALS method.

In the adhesive of the second embodiment according to the present invention,
One or more active hydrogen group-containing compounds (H) contain 50% by mass or more of active hydrogen group-containing compounds (HY) having a degree of branching of more than 0.5 as measured by GPC-MALS,
The hydroxyl group-terminated urethane prepolymer (UPH) has a branching degree of more than 0.6 and not more than 0.8 as measured by the GPC-MALS method.

The pressure-sensitive adhesive sheet of the present invention includes a base sheet and a pressure-sensitive adhesive layer comprising a cured product of the pressure-sensitive adhesive of the present invention.

According to the present invention, it is possible to form an adhesive layer that has good initial curability, suppresses an increase in adhesive strength even when exposed to a heat environment, particularly a hot and humid environment, and has good removability. and a pressure-sensitive adhesive sheet using the same.
According to the first embodiment of the present invention, the initial curability and the removability (effect of suppressing the increase in adhesive strength) when exposed to a thermal environment, particularly a hot and humid environment, are good. A pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer with good adhesion, scratch resistance, and adhesion to curved surfaces, and a pressure-sensitive adhesive sheet using the same can be provided.
According to the second embodiment of the present invention, the initial curability and the removability (effect of suppressing the increase in adhesive strength) when exposed to a thermal environment, particularly a hot and humid environment, are good, and the folding resistance is good. It is possible to provide a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer having good toughness, cuttability, and heat resistance, and a pressure-sensitive adhesive sheet using the same.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic cross section of the adhesive sheet of 1st Embodiment which concerns on this invention. FIG. 4 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to a second embodiment of the invention; FIG. 2 is an image diagram of an example of prepolymer production.

[Adhesive]
The pressure-sensitive adhesive of the present invention is
A hydroxyl group-terminated urethane prepolymer (UPH) (simply Also referred to as "prepolymer".) and
A pressure-sensitive adhesive containing a polyfunctional isocyanate compound (I),
The hydroxyl group-terminated urethane prepolymer (UPH) has a branching degree α (also simply referred to as "branching degree α") measured by the GPC-MALS method of 0.2 to 0.8, and is a removable urethane adhesive. is an agent.
The pressure-sensitive adhesive sheet of the present invention is a urethane-based pressure-sensitive adhesive sheet comprising a substrate sheet and an adhesive layer comprising a cured product of the pressure-sensitive adhesive of the present invention.

The "branching degree α" is an apparatus ("GPC-MALS" or "GPC-MALS-VISCO ), and is measured by a known method. For the measurement of the degree of branching α by GPC-MALS, refer to Patent Documents 1 to 4 mentioned in the section [Background Art].

The GPC method is a method in which a solution of a sample whose molecular weight is to be measured is passed through a column filled with a porous material such as silica, and the molecular weight is measured based on the elution time. A sample with a smaller molecular size will pass through a deeper portion within the pores of the porous material, resulting in a longer elution time. The molecular weight of the sample is determined by comparing the elution time with standards of known molecular weight.
The length of the elution time of the sample in the GPC method corresponds to the size of the molecule, but the size of the molecule does not strictly correlate with the size of the molecular weight. Depending on the polarity of the sample, the molecular weight cannot be measured accurately, since the molecular size changes depending on the affinity with the eluent. The molecular size also varies depending on the branching state of the molecule. Even if the molecular weight is the same, the more branches, the smaller the molecular size. Samples with the same elution time may have different actual molecular weights (absolute molecular weights) depending on the polarity or branching state of the molecules. put away.

In GPC-MALS, in addition to normal GPC measurement, a sample solution is irradiated with laser light of a specific wavelength and the intensity of scattered light caused by Rayleigh scattering is measured. Scattered light intensity varies with molecular size and branching state. For example, a sample with a small molecular size and no branching will have a single scattering point and a low scattered light intensity. A sample with a large molecular size and many branches has many scattering points and a high scattered light intensity. GPC-MALS also measures the intrinsic viscosity of the sample by VISCO. GPC-MALS also allows determination of absolute molecular weights.

式中、ｌｏｇ［η］は固有粘度、ｌｏｇＫは密度、Ｍｗは重量平均分子量、αは分岐度を示す。（プレ）ポリマー分子では、α値が小さい程、分岐が多く（高分岐であり）、球状またはそれに近い形状になり（概ね、α＜０．５の範囲）、α値が大きい程、分岐が少なく（低分岐であり）、棒状またはそれに近い形状になる（概ね、α＞０．８の範囲）。 The relationship between the intrinsic viscosity, the density, the weight average molecular weight (Mw), and the degree of branching α is represented by the Mark-Houwink-Sakurada formula (the following formula).

In the formula, log [η] is the intrinsic viscosity, log K is the density, Mw is the weight average molecular weight, and α is the degree of branching. In the (pre)polymer molecule, the smaller the α value, the more branches (highly branched) and the shape becomes spherical or nearly spherical (generally in the range of α < 0.5), and the larger the α value, the more branched. It is less branched (less branched) and has a rod-like or similar shape (generally in the range of α>0.8).

For example, as shown in FIG. 3, 3 molecules of relatively highly branched polyol (PO1), 5 molecules of relatively low branched polyol (PO2), and 7 molecules of relatively low branched polyisocyanate (PI1) can produce a relatively highly branched prepolymer (PP1), a relatively low branched prepolymer (PP2), or an intermediate branched prepolymer. The prepolymer (PP1) and the prepolymer (PP2) have the same molecular weight, but different branching states, different molecular sizes and molecular morphologies. In addition, FIG. 3 is an image diagram of a reaction example.
As described in the section [Problems to be Solved by the Invention], there is no document describing the degree of branching α of the prepolymer or its raw material for urethane pressure-sensitive adhesives.
In the present invention, the branching degree α of the prepolymer or its raw material is optimized to optimize the properties of the pressure-sensitive adhesive.
The branching degree α of the prepolymer can be adjusted by the branching degree α of each of the raw materials used, the combination of the raw materials used, the quantitative ratio of the raw materials used, the reaction conditions, the reaction procedure, and the like.

The hydroxyl group-terminated urethane prepolymer (UPH) contained in the adhesive of the present invention has a branching degree α of 0.2 to 0.8.
When the degree of branching α is less than 0.2, the prepolymer molecules are highly branched (highly branched) and spherical or nearly spherical. Adhesives containing highly branched hydroxyl-terminated urethane prepolymers (UPH) exhibit excessive intramolecular reactions during the reaction between the hydroxyl-terminated urethane prepolymers (UPH) and the curing agent, inhibiting the progress of intermolecular cross-linking reactions. Therefore, the initial curability tends to decrease. Furthermore, the re-peelability of the adhesive layer is reduced mainly at locations where the degree of intermolecular cross-linking is low, and after the adhesive sheet is peeled off from the finger and the adherend, etc., the adhesive layer component remains on the finger and the adherend. "Adhesive residue" (also called "adherend contamination") is likely to occur. In addition, when exposed to a heat environment, particularly a hot and humid environment, the adhesive strength increases significantly, and the removability tends to decrease.

When the degree of branching α exceeds 0.8, the prepolymer molecules are less branched (low-branched) and have a rod-like or similar shape. Adhesives containing low-branched hydroxyl-terminated urethane prepolymers (UPH) have a rod-like or similar shape, making it difficult to form a high-density crosslinked structure, resulting in poor initial curing. It's easy to do. Furthermore, as a result of insufficient crosslinked structure, the removability of the adhesive layer is reduced, and after the adhesive sheet is peeled off from the finger, the adherend, etc., the components of the adhesive layer remain on the finger, the adherend, etc. "Adhesive residue" (adherent contamination) is more likely to occur. In addition, when exposed to a heat environment, particularly a hot and humid environment, the adhesive strength increases significantly, and the removability tends to decrease.

By using a hydroxyl-terminated urethane prepolymer (UPH) having a branching degree α in the range of 0.2 to 0.8, intramolecular reaction and molecular Since the inter-crosslinking reaction proceeds appropriately and a high-density crosslinked structure is formed at an early stage, the initial curability is good, and the increase in adhesive strength is suppressed even when exposed to a heat environment, especially a hot and humid environment. A pressure-sensitive adhesive that can form a pressure-sensitive adhesive layer having good removability can be provided.

(First embodiment)
In the adhesive according to the first embodiment of the present invention, one or more active hydrogen group-containing compounds (H) are active hydrogen group-containing compounds having a branching degree α of 0.5 or less as measured by GPC-MALS method. The hydroxyl group-terminated urethane prepolymer (UPH) containing 50% by mass or more of (HX) has a branching degree α of 0.2 to 0.6 as measured by the GPC-MALS method.
In the pressure-sensitive adhesive of the first embodiment, the intramolecular cross-linking reaction progresses early and predominantly while maintaining the progress of the intermolecular cross-linking reaction. In addition, it is possible to achieve both a dense structure due to intramolecular cross-linking and a sparse structure due to intermolecular cross-linking. It is possible to form an adhesive layer with good scratch resistance and adhesion to curved surfaces.

In the pressure-sensitive adhesive of the first embodiment, since the above effects can be effectively obtained, the hydroxyl group-terminated urethane prepolymer (UPH) has a branching degree α of 0.3 to 0.3 as measured by the GPC-MALS method. It is preferably 6, more preferably 0.4 to 0.6.

In the pressure-sensitive adhesive of the first embodiment, since the above effects can be effectively obtained, the one or more active hydrogen group-containing compounds (H) have a degree of branching α of 0.5 as measured by the GPC-MALS method. The active hydrogen group-containing compound (HY) containing 50% by mass or more and less than 100% by mass of the following active hydrogen group-containing compound (HX) and having a branching degree α of more than 0.5 as measured by the GPC-MALS method is 0. It is preferable to contain more than mass % and less than 50 mass %.
When the active hydrogen group-containing compound (H) satisfies the above stipulations, the contrast between the sparse and dense urethane bonds generated becomes stronger, so that the sea-island structure is effectively enhanced. .

In the pressure-sensitive adhesive of the first embodiment, since the above effects can be effectively obtained, the one or more active hydrogen group-containing compounds (H) have a degree of branching α of 0.3 as measured by the GPC-MALS method. It preferably contains an active hydrogen group-containing compound (HX-S) having the following, more preferably an active hydrogen group-containing compound having a branching degree α of 0.2 or less.

More preferably, the pressure-sensitive adhesive of the first embodiment contains 70% by mass or more of one or more active hydrogen group-containing compounds (HX) having a branching degree α of 0.5 or less. More preferably, the pressure-sensitive adhesive of the first embodiment contains more than 0% by mass and less than 30% by mass of one or more active hydrogen group-containing compounds (HY) having a branching degree α of more than 0.5, and more than 10% by mass. It is particularly preferred to contain less than 30% by mass.
When the active hydrogen group-containing compound (H) satisfies the above-mentioned requirements, denser urethane bonds are formed, and the above effects due to the development of the sea-island structure are effectively enhanced.

(Second embodiment)
In the adhesive according to the second embodiment of the present invention, one or more active hydrogen group-containing compounds (H) are active hydrogen group-containing compounds having a branching degree α of more than 0.5 as measured by GPC-MALS method. The hydroxyl group-terminated urethane prepolymer (UPH) containing (HY) in an amount of 50% by mass or more has a branching degree α of more than 0.6 and not more than 0.8 as measured by the GPC-MALS method.
In the pressure-sensitive adhesive of the second embodiment, due to the moderate branched structure contained in the hydroxyl group-terminated urethane prepolymer (UPH), a cross-linked structure is formed at an early stage. It is possible to form an adhesive layer with good re-peelability (effect of suppressing increase in adhesive strength) when applied. Also, in the pressure-sensitive adhesive of the second embodiment, a structure having a relatively sparse cross-linking density is formed, so that a pressure-sensitive adhesive layer with good folding endurance, cutting properties, and heat resistance can be formed.

In the adhesive of the second embodiment, a uniform and appropriate crosslinked structure is formed, and the above effects are effectively obtained. Therefore, the hydroxyl group-terminated urethane prepolymer (UPH) has branched More preferably, the degree α is 0.7 to 0.8.

In the pressure-sensitive adhesive of the second embodiment, a uniform and appropriate crosslinked structure is formed, and the above effects are effectively obtained. 50% by mass or more and less than 100% by mass of an active hydrogen group-containing compound (HY) having a measured branching degree α of more than 0.5, and a branching degree α measured by the GPC-MALS method of 0.5 or less. It preferably contains more than 0% by mass and less than 50% by mass of the active hydrogen group-containing compound (HX).

In the pressure-sensitive adhesive of the second embodiment, a uniform and appropriate crosslinked structure is formed, and the above effects are effectively obtained. It preferably contains 50% by mass or more of an active hydrogen group-containing compound (HY-L) having a measured branching degree α of more than 0.6.

In the pressure-sensitive adhesive of the second embodiment, it is more preferable that the branching degree α of the active hydrogen group-containing compound (HY) is 0.8 or more.
More preferably, the pressure-sensitive adhesive of the second embodiment contains 70% by mass or more of one or more active hydrogen group-containing compounds (HY). More preferably, the pressure-sensitive adhesive of the second embodiment contains more than 0% by mass and less than 30% by mass of one or more active hydrogen group-containing compounds (HX) having a branching degree α of 0.5 or less, and 10% by mass or more. It is particularly preferred to contain less than 30% by mass.

(Hydroxyl group-terminated urethane prepolymer (UPH))
A hydroxyl group-terminated urethane prepolymer (UPH) is a reaction product obtained by copolymerizing one or more active hydrogen group-containing compounds (H) and one or more polyisocyanates (N). The copolymerization reaction can be carried out in the presence of one or more catalysts, if desired. One or more solvents may be used in the copolymerization reaction, if desired.
In the present invention, the degree of branching α of each of the raw materials used, the combination of the raw materials used, the quantitative ratio of the raw materials used, the reaction conditions, the reaction procedure, etc. are adjusted to obtain hydroxyl-terminated urethane prepolymers (UPH). The branching degree α of is within the range of 0.2 to 0.8.

In the adhesive of the first embodiment, the weight average molecular weight (Mw) of the hydroxyl-terminated urethane prepolymer (UPH) is preferably 40,000 or more, more preferably 60,000 or more, and particularly preferably 80,000 or more. When Mw is at least the above lower limit, initial curability and removability are improved.

In the adhesive of the second embodiment, the weight average molecular weight (Mw) of the hydroxyl-terminated urethane prepolymer (UPH) is preferably 10,000 or more, more preferably 20,000 or more, and particularly preferably 30,000 or more. When Mw is at least the above lower limit, initial curability, removability, and heat resistance are improved.

<Active hydrogen group-containing compound (H)>
The active hydrogen group-containing compound (H) is a compound having a plurality of active hydrogen groups in one molecule.
Examples of active hydrogen groups include a hydroxyl group (hydroxy group), a mercapto group, and an amino group (unless otherwise specified, the amino group includes an imino group). Examples of active hydrogen group-containing compounds (H) include polyols having multiple hydroxyl groups in one molecule, polyamines having multiple amino groups in one molecule, aminoalcohols having amino groups and hydroxyl groups in one molecule, and one molecule of Among them are polythiols having multiple mercapto groups. These active hydrogen group-containing compounds (H) may be nonpolymers or polymers. These can be used alone or in combination of two or more.
Among them, polyols are preferred. Since polyamines and polythiols are highly reactive with polyisocyanates and have short pot lives, they are preferably used in combination with polyols.

Polyols that can be used as the active hydrogen group-containing compound (H) include polyester polyols, polyether polyols, polyacrylic polyols, polycaprolactone polyols, polycarbonate polyols, and castor oil-based polyols. Among them, polyester polyols, polyether polyols, and combinations thereof are preferable because they have appropriate flexibility and the adhesive strength, folding endurance, and curved surface adhesion of the adhesive layer are favorable. Furthermore, the one or more active hydrogen group-containing compounds (H) particularly preferably contain a polyether polyol, since the hydrolysis resistance becomes favorable.

A known polyester polyol can be used as the active hydrogen group-containing compound (H). Examples of polyester polyols include compounds (esterified products) obtained by an esterification reaction between one or more polyol components and one or more acid components.

Examples of raw polyol components include ethylene glycol (EG), propylene glycol (PG), diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 2-ethyl-1,3- hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerin, trimethylolpropane, pentaerythritol, and the like. be done.

Acid components of raw materials include succinic acid, methylsuccinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, 1,14-tetradecanedioic acid, dimer acid, 2-methyl-1, 4-cyclohexanedicarboxylic acid, 2-ethyl-1,4-cyclohexanedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, and acid anhydrides thereof etc.

A known polyether polyol can be used as the active hydrogen group-containing compound (H). Examples of polyether polyols include compounds (addition polymers) obtained by addition polymerization of one or more oxirane compounds using an active hydrogen group-containing compound having a plurality of active hydrogen groups in one molecule as an initiator. .

Examples of initiators include hydroxyl group-containing compounds and amines. Specifically, two compounds such as ethylene glycol (EG), propylene glycol (PG), 1,4-butanediol, neopentyl glycol, butylethylpentanediol, N-aminoethylethanolamine, isophoronediamine, and xylylenediamine. functional initiators; trifunctional initiators such as glycerin, trimethylolpropane, and triethanolamine; and tetrafunctional initiators such as pentaerythritol, ethylenediamine, and aromatic diamines.
Oxirane compounds include alkylene oxides (AO) such as ethylene oxide (EO), propylene oxide (PO), and butylene oxide (BO); tetrahydrofuran (THF), and the like.

As the polyether polyol, an alkylene oxide adduct of an active hydrogen group-containing compound (also referred to as polyoxyalkylene polyol) is preferable. Among them, polyethylene glycol (PEG), polypropylene glycol (PPG), PPG with ethylene oxide (EO) added to the end (PPG-EO), and bifunctional polyether polyols such as polyalkylene glycols such as polytetramethylene glycol; Trifunctional polyether polyols such as alkylene oxide adducts of glycerin are preferred.

Examples of polyamines that can be used as the active hydrogen group-containing compound (H) include ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6 -hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,12-dodecanediamine, 1,14-tetradecanediamine, 1,16-hexadecane Diamine, hexamethylenediamine, trimethylhexamethylenediamine, iminobispropylamine, methyliminobispropylamine, 1,5-diamino-2-methylpentane, isophoronediamine, 1,3-bisaminomethylcyclohexane, 1-cyclohexylamino- 3-Aminopropane, 3-aminomethyl-3,3,5-trimethyl-cyclohexylamine, norbornane dimethyleneamine, metaxylylenediamine (MXDA), hexamethylenediamine carbamate, diethylenetriamine, triethylenetetramine, tetraethylenepenta amine, and aliphatic polyamines such as pentaethylenehexamine; 3,3′-dichloro-4,4′-diaminodiphenylmethane (MOCA), 4,4′-diaminodiphenylmethane, 2,4′-diaminodiphenylmethane, 3,3′ -diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,2'-diaminobiphenyl, 3,3'-diaminobiphenyl, 2,4-diaminophenol, 2,5-diaminophenol, o-phenylenediamine, m-phenylene Diamines, p-phenylenediamine, 2,3-tolylenediamine, 2,4-tolylenediamine, 2,5-tolylenediamine, 2,6-tolylenediamine, 3,4-tolylenediamine, and diethyltoluene aromatic polyamines such as diamine;

Amino alcohols that can be used as the active hydrogen group-containing compound (H) include monoethanolamine, diethanolamine, 2-amino-2-methyl-1-propanol, tri(hydroxymethyl)aminomethane, and 2-amino-2 -monoamines having a hydroxyl group such as ethyl-1,3-propanediol; diamines having a hydroxyl group such as N-(2-hydroxypropyl)ethanolamine; and the like.

Polythiols that can be used as the active hydrogen group-containing compound (H) include methanedithiol, 1,3-butanedithiol, 1,4-butanedithiol, 2,3-butanedithiol, 1,2-benzenedithiol, 1, 3-benzenedithiol, 1,4-benzenedithiol, 1,10-decanedithiol, 1,2-ethanedithiol, 1,6-hexanedithiol, 1,9-nonanedithiol, 1,8-octanedithiol, 1,5 -pentanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, toluene-3,4-dithiol, 3,6-dichloro-1,2-benzenedithiol, 1,5-naphthalenedithiol, 1,2- benzenedimethanethiol, 1,3-benzenedimethanethiol, 1,4-benzenedimethanethiol, 4,4'-thiobisbenzenethiol, 2,5-dimercapto-1,3,4-thiadiazole, 1,8 -dimercapto-3,6-dioxaoctane, 1,5-dimercapto-3-thiapentane, 2-di-n-butylamino-4,6-dimercapto-s-triazine, and thiol group-terminated polymers (such as polysulfide polymers) etc.

The one or more active hydrogen group-containing compounds (H) can include a bifunctional active hydrogen group-containing compound and/or a tri- or more functional active hydrogen group-containing compound. In general, a bifunctional active hydrogen group-containing compound has two-dimensional crosslinkability and can impart appropriate flexibility to the pressure-sensitive adhesive layer. The trifunctional or higher active hydrogen group-containing compound has three-dimensional crosslinkability and can impart appropriate hardness to the pressure-sensitive adhesive layer. By selecting the number of functional groups (the number of active hydrogen groups) of each active hydrogen group-containing compound (H), it is possible to adjust the adhesive strength, cohesive strength, removability, and other properties of the urethane-based pressure-sensitive adhesive. The number of functional groups of each material can be selected so that properties such as adhesive strength, cohesive strength, and removability are within preferred ranges depending on the application.
Since it is easy to achieve both adhesive strength and removability, the one or more active hydrogen group-containing compounds (H) should contain a bifunctional active hydrogen group-containing compound and a tri- or more functional active hydrogen group-containing compound. is preferred.

The active hydrogen group-containing compound (H) is preferably an active hydrogen group-containing compound (HX) having a branching degree α of 0.5 or less measured by the GPC-MALS method, and a branched compound measured by the GPC-MALS method. It includes an active hydrogen group-containing compound (HY) whose degree α is greater than 0.5.
The branching degree α of the active hydrogen group-containing compound (H) can be adjusted by the structure of the raw materials used, the quantitative ratio of the raw materials used, the combination of the raw materials used, the reaction conditions, the reaction procedure, and the like. .
Even if the raw material composition is the same, if the molecular weight of the active hydrogen group-containing compound (H) changes, the degree of branching α will change. Even if the active hydrogen group-containing compound (H) has the same molecular weight, if the branch structure changes, the branching degree α will change. If the branched structure of the active hydrogen group-containing compound (H) changes, the number of functional groups may change depending on the composition.

The number of functional groups of the active hydrogen group-containing compound (H) is not particularly limited. The number of functional groups of the active hydrogen group-containing compound (HX) having a branching degree α of 0.5 or less is preferably trifunctional or more from the viewpoint of easily obtaining a highly branched structure. The number of functional groups of the active hydrogen group-containing compound (HY) having a branching degree α of more than 0.5 is preferably bifunctional or less from the viewpoint of easily obtaining a low-branched structure.

The number average molecular weight (Mn) of the active hydrogen group-containing compound (H) is not particularly limited. Mn of the active hydrogen group-containing compound (H) is preferably from 50 to 20,000, more preferably from 100 to 15,000, and particularly preferably from 400 to 10,000, since the adhesion and wettability of the adhesive layer are favorable.
Mn of the active hydrogen group-containing compound (H) affects the degree of branching α. However, as described above, the degree of branching α is also affected by factors other than Mn.

The active hydrogen group-containing compound (H) preferably contains an active hydrogen group-containing compound having a primary hydroxyl group. In this case, the initial curability of the adhesive can be improved.

<Polyisocyanate (N)>
A known polyisocyanate (N) can be used, including aromatic polyisocyanate, aliphatic polyisocyanate, and alicyclic polyisocyanate.

Aromatic polyisocyanates include 1,3-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tri diisocyanate, 4,4′-toluidine diisocyanate, 2,4,6-triisocyanatotoluene, 1,3,5-triisocyanatobenzene, dianisidine diisocyanate, 4,4′-diphenyl ether diisocyanate, and 4,4′,4 "-triphenylmethane triisocyanate, ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,ω'-diisocyanate-1,4-dimethylbenzene, ω,ω'-diisocyanate-1,4-diethylbenzene, 1 ,4-tetramethylxylylene diisocyanate and 1,3-tetramethylxylylene diisocyanate.

Aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, and dodecamethylene diisocyanate. , and 2,4,4-trimethylhexamethylene diisocyanate.

Alicyclic polyisocyanates include isophorone diisocyanate (IPDI), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6 -cyclohexanediisocyanate, 4,4′-methylenebis(cyclohexylisocyanate), and 1,4-bis(isocyanatomethyl)cyclohexane, and the like.

Other polyisocyanates include trimethylolpropane adduct, biuret, allophanate, and trimers of the above polyisocyanates (this trimer contains an isocyanurate ring).

Preferred raw material blending ratios of the hydroxyl group-terminated urethane prepolymer (UPH) are as follows.
The ratio (NCO/H ratio) of the number of moles of isocyanate groups (NCO) possessed by the polyisocyanate (N) to the total number of moles of the active hydrogen groups (H) possessed by the active hydrogen group-containing compounds (H) of a plurality of types is 0.5. It is preferable to determine the mixing ratio of the raw materials so that it is 20 to 0.95, preferably 0.40 to 0.85. The closer the NCO/H ratio is to 1, the more easily gelation tends to occur during the synthesis of the hydroxyl-terminated urethane prepolymer (UPH). If the NCO/H ratio is 0.95 or less, it is possible to effectively suppress gelation during the synthesis of hydroxyl-terminated urethane prepolymer (UPH).

<Catalyst>
If necessary, one or more catalysts can be used for the polymerization of the hydroxyl-terminated urethane prepolymer (UPH). Known catalysts can be used, including tertiary amine compounds and organometallic compounds.
Tertiary amine compounds include triethylamine, triethylenediamine, and 1,8-diazabicyclo(5,4,0)-undecene-7 (DBU).
Examples of organometallic compounds include tin-based compounds and non-tin-based compounds.
Tin compounds include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate, dibutyltin dilaurate (DBTDL), dibutyltin diacetate, dioctyltin dilaurate, dibutyltin sulfide, tributyltin sulfide, tributyltin oxide. , tributyltin acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, and tin 2-ethylhexanoate.
Non-tin compounds include titanium compounds such as dibutyl titanium dichloride, tetrabutyl titanate, and butoxy titanium trichloride; lead compounds such as lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate; - iron-based, such as iron ethylhexanoate and iron acetylacetonate; cobalt-based, such as cobalt benzoate and cobalt 2-ethylhexanoate; zinc-based, such as zinc naphthenate and zinc 2-ethylhexanoate; A zirconium system is mentioned.
The type and amount of catalyst to be added can be appropriately designed within a range in which the reaction proceeds well.

When multiple types of active hydrogen group-containing compounds (H) with different reactivities are used in combination, the difference in reactivity between them may lead to poor polymerization stability or cloudiness of the reaction solution in a single catalyst system. be. In this case, by using two or more kinds of catalysts, the reaction (for example, reaction rate, etc.) can be easily controlled, and the above problem can be solved. In a system in which a plurality of active hydrogen group-containing compounds (H) with different reactivities are used in combination, it is preferable to use two or more catalysts. Combinations of two or more catalysts are not particularly limited, and include tertiary amine/organometallic, tin-based/non-tin-based, tin-based/tin-based, and the like. Tin-based/tin-based are preferred, and dioctyltin dilaurate and tin 2-ethylhexanoate are more preferred.
The mass ratio of tin 2-ethylhexanoate and dioctyltin dilaurate (tin 2-ethylhexanoate/dioctyltin dilaurate) is not particularly limited, and is preferably more than 0 and less than 1, more preferably 0.2 to 0.8. be. When the mass ratio is less than 1, the catalyst activity is well balanced, the gelation and cloudiness of the reaction solution are effectively suppressed, and the polymerization stability is further improved.

The amount of one or more catalysts used is not particularly limited, and is preferably 0.01 to 0.01 with respect to the total amount of one or more active hydrogen group-containing compounds (H) and one or more polyisocyanates (N). It is 1.0% by mass.

<Solvent>
If necessary, one or more solvents can be used for the polymerization of the hydroxyl-terminated urethane prepolymer (UPH). A known solvent can be used, including methyl ethyl ketone, ethyl acetate, toluene, xylene, and acetone. Ethyl acetate, toluene and the like are particularly preferred from the viewpoint of the solubility of the hydroxyl group-terminated urethane prepolymer (UPH) and the boiling point of the solvent.

<Polymerization method of hydroxyl group-terminated urethane prepolymer (UPH)>
The polymerization method for the hydroxyl group-terminated urethane prepolymer (UPH) is not particularly limited, and known polymerization methods such as bulk polymerization and solution polymerization can be applied.
As a polymerization procedure for the hydroxyl group-terminated urethane prepolymer (UPH),
Procedure 1) One or more active hydrogen group-containing compounds (H), one or more polyisocyanates (N), optionally one or more catalysts, and optionally one or more solvents all together Procedure for charging the flask;
Procedure 2) One or more active hydrogen group-containing compounds (H), optionally one or more catalysts, and optionally one or more solvents are charged in a flask, to which one or more polyisocyanates ( N) can be added dropwise.
In the polymerization method of procedure 1), there is a possibility that the reaction may proceed rapidly in some parts, resulting in the formation of a polymer with a low degree of branching as the main component or the formation of a gel. On the other hand, in the polymerization method of procedure 2), the reaction can be controlled mildly and a polymer with a preferred degree of branching can be easily produced. Therefore, the polymerization method of procedure 2) is more preferable.

When using multiple types of active hydrogen group-containing compounds (H) and/or polyisocyanates (N), the reaction may be carried out in multiple stages.
For example, in the reaction example shown in FIG. 3, a relatively highly branched polyol (PO1), a relatively low branched polyol (PO2), and a relatively low branched polyisocyanate (PI1) are reacted together. In this case, there is a high possibility that a branched prepolymer intermediate between the relatively highly branched prepolymer (PP1) and the relatively low branched prepolymer (PP2) is produced. A relatively highly branched polyol (PO1) and a relatively low branched polyisocyanate (PI1) are reacted first, and then a relatively low branched polyol (PO2) is reacted to obtain a relatively highly branched prepolymer. It becomes easier to obtain a polymer.

The reaction temperature when using a catalyst is preferably less than 100°C, more preferably 50-95°C, particularly preferably 60-85°C. If the reaction temperature is 100° C. or higher, it may become difficult to control the reaction rate, polymerization stability, and the like, making it difficult to produce a hydroxyl-terminated urethane prepolymer (UPH) having a desired molecular weight. The reaction temperature when no catalyst is used is preferably 100° C. or higher, more preferably 110° C. or higher.

(Polyfunctional isocyanate compound (I))
A known compound can be used as the polyfunctional isocyanate compound (I), and the compounds exemplified as the polyisocyanate (N) which is a raw material of the hydroxyl group-terminated urethane prepolymer (UPH) (specifically, aromatic polyisocyanate, aliphatic Polyisocyanates, araliphatic polyisocyanates, alicyclic polyisocyanates, and their trimethylolpropane adducts/biurets/allophanates/trimers) can be used.

The amount of polyfunctional isocyanate compound (I) to be blended is not particularly limited. The ratio of the number of moles of isocyanate groups (NCO) in the polyisocyanate (I) to the total number of moles of active hydrogen groups (H) in the hydroxyl-terminated urethane prepolymer (UPH) (NCO/H ratio) is 0.20 to 4. 0.00, preferably 0.40 to 3.00.

(Plasticizer (P))
From the viewpoint of reducing the adhesive strength of the adhesive layer and improving the wettability, the adhesive of the present invention can further contain one or more plasticizers (P) as necessary. The plasticizer (P) is not particularly limited, and organic acid esters are preferable from the viewpoint of compatibility with other components.

The content of the plasticizer (P) is preferably 10 parts by mass or more with respect to 100 parts by mass of the hydroxyl group-terminated urethane prepolymer (UPH). The upper limit of the content of the plasticizer (P) is not particularly limited, and is preferably 300 parts by mass or less, more preferably 150 parts by mass or less. When the content of the plasticizer (P) is within the above range, removability is improved.

Esters of monobasic or polybasic acids with alcohols include, for example, isostearyl laurate, isopropyl myristate, isocetyl myristate, octyldodecyl myristate, isostearyl palmitate, isocetyl stearate, octyldodecyl oleate, and phthalate. Dibutyl acid, dioctyl phthalate, diheptyl phthalate, dibenzyl phthalate, butyl benzyl phthalate, diisodecyl adipate, diisostearyl adipate, dibutyl sebacate, diisocetyl sebacate, acetyl tributyl citrate, tributyl trimellitate, trimellit trioctyl acid, trihexyl trimellitate, trioleyl trimellitate, triisocetyl trimellitate, and the like.

Other esters of acids and alcohols include unsaturated fatty acids or branched acids such as myristoleic acid, oleic acid, linoleic acid, linolenic acid, isopalmitic acid, and isostearic acid, and ethylene glycol, propylene glycol, glycerin. , trimethylolpropane, pentaerythritol, and esters with alcohols such as sorbitan.

Examples of esters of monobasic or polybasic acids with polyalkylene glycol include polyethylene glycol dihexylate, polyethylene glycol di-2-ethylhexylate, polyethylene glycol dilaurate, polyethylene glycol dioleate, and dipolyethylene glycol methyl adipate. ether and the like.

The molecular weight (formula weight or Mn) of the organic acid ester is preferably 250 to 1,000, more preferably 400 to 900, and particularly preferably 500 to 850 from the viewpoint of improving wettability. If the molecular weight is 250 or more, the heat resistance of the adhesive layer will be good, and if the molecular weight is 1,000 or less, the wettability of the adhesive will be good.

(solvent)
The pressure-sensitive adhesive of the present invention can contain one or more solvents, if desired. A known solvent can be used, including methyl ethyl ketone, ethyl acetate, toluene, xylene, and acetone. Ethyl acetate, toluene, and the like are particularly preferred from the viewpoint of the solubility of the hydroxyl group-terminated urethane prepolymer (UPH) and the boiling point of the solvent.

(Anti-alteration agent)
The pressure-sensitive adhesive of the present invention may optionally contain one or more anti-deterioration agents. Thereby, deterioration of various properties due to long-term use of the adhesive layer can be suppressed. Anti-deterioration agents include anti-hydrolysis agents, antioxidants, UV absorbers, light stabilizers, and the like.

<Hydrolysis resistant agent>
When a hydrolysis reaction occurs in the adhesive layer in a (wet) heat environment or the like to generate carboxy groups, a hydrolysis-resistant agent can be used to block the carboxy groups. Examples of hydrolysis-resistant agents include carbodiimide-based, oxazoline-based, and epoxy-based agents. Among these, carbodiimide-based compounds are preferable from the viewpoint of the hydrolysis-suppressing effect.

A carbodiimide hydrolysis resistant agent is a compound having one or more carbodiimide groups in one molecule.
Examples of monocarbodiimide compounds include dicyclohexylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, diphenylcarbodiimide, and naphthylcarbodiimide.
A polycarbodiimide compound can be produced by subjecting a diisocyanate to a decarboxylation condensation reaction in the presence of a carbodiimidation catalyst. Here, examples of diisocyanate include 4,4'-diphenylmethane diisocyanate, 3,3'-dimethoxy-4,4'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 4,4 '-diphenyl ether diisocyanate, 3,3'-dimethyl-4,4'-diphenyl ether diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, tetramethylxylylene diisocyanate, and the like. Carbodiimidation catalysts include 1-phenyl-2-phospholene-1-oxide, 3-methyl-2-phospholene-1-oxide, 1-ethyl-3-methyl-2-phospholene-1-oxide, 1-ethyl- Phosphorene oxides such as 2-phospholene-1-oxide, and 3-phospholene isomers thereof, and the like.

Examples of oxazoline hydrolysis stabilizers include 2,2′-o-phenylenebis(2-oxazoline), 2,2′-m-phenylenebis(2-oxazoline), 2,2′-p-phenylenebis (2-oxazoline), 2,2′-p-phenylenebis(4-methyl-2-oxazoline), 2,2′-m-phenylenebis(4-methyl-2-oxazoline), 2,2′-p -phenylenebis(4,4'-dimethyl-2-oxazoline), 2,2'-m-phenylenebis(4,4'-dimethyl-2-oxazoline), 2,2'-ethylenebis(2-oxazoline) , 2,2′-tetramethylenebis(2-oxazoline), 2,2′-hexamethylenebis(2-oxazoline), 2,2′-octamethylenebis(2-oxazoline), 2,2′-ethylenebis (4-methyl-2-oxazoline), and 2,2'-diphenylenebis(2-oxazoline).

Examples of epoxy-based hydrolysis-resistant agents include diglycidyl ethers of aliphatic diols such as 1,6-hexanediol, neopentyl glycol, and polyalkylene glycol; sorbitol, sorbitan, polyglycerol, pentaerythritol, diglycerol, and glycerol. , and polyglycidyl ethers of aliphatic polyols such as trimethylolpropane; polyglycidyl ethers of cycloaliphatic polyols such as cyclohexanedimethanol; terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, trimellitic acid, adipic acid, and sebacic acid, etc. diglycidyl esters or polyglycidyl esters of aliphatic or aromatic polycarboxylic acids of; resorcinol, bis-(p-hydroxyphenyl)methane, 2,2-bis-(p-hydroxyphenyl)propane, tris-(p -hydroxyphenyl)methane, and diglycidyl or polyglycidyl ethers of polyhydric phenols such as 1,1,2,2-tetrakis(p-hydroxyphenyl)ethane; N,N-diglycidylaniline, N,N-di N-glycidyl derivatives of amines such as glycidyltoluidine and N,N,N',N'-tetraglycidyl-bis-(p-aminophenyl)methane; triglycidyl derivatives of aminophenols; triglycidyl tris(2-hydroxyethyl ) isocyanurate and triglycidyl isocyanurate; and epoxy resins such as ortho-cresol type epoxy resins and phenol novolac type epoxy resins.

The amount of hydrolysis resistant agent added is not particularly limited, and is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 4.5 parts by mass, relative to 100 parts by mass of hydroxyl-terminated urethane prepolymer (UPH). , particularly preferably 0.5 to 3 parts by mass.

<Antioxidant>
Antioxidants include radical scavengers and peroxide decomposers. Examples of radical scavengers include phenol compounds and amine compounds. Examples of peroxide decomposers include sulfur-based compounds and phosphorus-based compounds.

Examples of phenol compounds include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearin-β-(3,5 -di-t-butyl-4-hydroxyphenyl)propionate, 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), 3,9-bis[1,1-dimethyl-2- [β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]2,4,8,10-tetraoxaspiro[5,5]undecane, benzenepropanoic acid, 3,5- bis(1,1-dimethylethyl)-4-hydroxy-, C7-C9 side chain alkyl ester, 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1, 3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tetrakis-[methylene-3-(3′,5′-di-t-butyl -4′-hydroxyphenyl)propionate]methane, bis[3,3′-bis-(4′-hydroxy-3′-t-butylphenyl)butyric acid]glycol ester, 1,3,5-tris(3 ',5'-di-t-butyl-4'-hydroxybenzyl)-S-triazine-2,4,6-(1H,3H,5H)trione, and tocopherol.

Examples of sulfur-based antioxidants include dilauryl 3,3'-thiodipropionate, dimyristyl 3,3'-thiodipropionate, and distearyl 3,3'-thiodipropionate.

Phosphorus compounds include, for example, triphenylphosphite, diphenylisodecylphosphite, 4,4′-butylidene-bis(3-methyl-6-tert-butylphenylditridecyl)phosphite, cyclic neopentanetetrayl bis(octadecylphosphite), tris(nonylphenyl)phosphite, tris(monononylphenyl)phosphite, tris(dinonylphenyl)phosphite, diisodecylpentaerythritol diphosphite, 9,10-dihydro-9-oxa- 10-phosphaphenanthrene-10-oxide, 10-(3,5-di-tert-butyl-4-hydroxybenzyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10 -decyloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene, tris(2,4-di-tert-butylphenyl)phosphite, cyclic neopentanetetraylbis(2,4-di-tert -butylphenyl)phosphite, cyclic neopentanetetraylbis(2,6-di-tert-butyl-4-methylphenyl)phosphite, and 2,2-methylenebis(4,6-di-tert-butylphenyl) ) octyl phosphite and the like.

By using an antioxidant, it is possible to prevent thermal deterioration of the hydroxyl group-terminated urethane prepolymer (UPH).
The amount of the antioxidant added is not particularly limited, and is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, particularly preferably 0.1 to 3 parts by mass, based on 100 parts by mass of the hydroxyl group-terminated urethane prepolymer (UPH). is 0.2 to 2 parts by mass.

As the antioxidant, from the viewpoint of stability and antioxidant effect, it is preferable to use one or more phenolic compounds that are radical scavengers. One or more phenolic compounds that are radical scavengers and a peroxide decomposer are It is more preferable to use together with one or more phosphorus-based compounds. In addition, as antioxidants, it is particularly preferable to use a combination of a phenolic compound that is a radical scavenger and a phosphorus compound that is a peroxide decomposer, and to use these antioxidants in combination with the above-mentioned anti-hydrolysis agent. .

<Ultraviolet absorber>
Examples of ultraviolet absorbers include benzophenone-based compounds, benzotriazole-based compounds, salicylic acid-based compounds, oxalic acid anilide-based compounds, cyanoacrylate-based compounds, and triazine-based compounds.
The amount of the ultraviolet absorber to be added is such that the initiation and progress of polymerization of the radically polymerizable monomer (MX) due to irradiation with active energy rays are not inhibited, and the radicals are easily absorbed by ambient light such as fluorescent light and sunlight. It can be appropriately designed within a range in which the reaction of the polymerizable monomer (MX) is not initiated. When the radically polymerizable monomer (MX) is UV curable, the amount of UV absorber to be added is designed according to the type of UV absorber, and the wavelength range and integrated amount of UV light irradiated to the adhesive layer. be done. The amount of the ultraviolet absorber to be added is preferably 0.01 to 3 parts by mass, more preferably 0.1 to 2.5 parts by mass, particularly preferably 0, per 100 parts by mass of the hydroxyl group-terminated urethane prepolymer (UPH). .2 to 2 parts by mass.

<Light stabilizer>
Light stabilizers include hindered amine compounds and hindered piperidine compounds. The amount of the light stabilizer added is not particularly limited, and is preferably 0.01 to 2 parts by mass, more preferably 0.1 to 1.5 parts by mass, based on 100 parts by mass of the hydroxyl-terminated urethane prepolymer (UPH). Particularly preferably, it is 0.2 to 1 part by mass.

(Antistatic agent (AS))
The adhesive of the present invention can optionally contain one or more antistatic agents (AS). Antistatic agents (AS) include inorganic salts, ionic liquids, ionic solids, surfactants, etc. Among them, ionic liquids and ionic solids are preferred. Incidentally, the “ionic liquid” is also referred to as a room temperature molten salt, and is a salt that is fluid at 25°C.

Examples of inorganic salts include sodium chloride, potassium chloride, lithium chloride, lithium perchlorate, ammonium chloride, potassium chlorate, aluminum chloride, copper chloride, ferrous chloride, ferric chloride, ammonium sulfate, potassium nitrate, sodium nitrate. , sodium carbonate, and sodium thiocyanate.

Ionic liquids containing imidazolium ions include, for example, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide, and 1-butyl -3-methylimidazolium bis(trifluoromethylsulfonyl)imide and the like.

Ionic liquids containing pyridinium ions include, for example, 1-methylpyridinium bis(trifluoromethylsulfonyl)imide, 1-butylpyridinium bis(trifluoromethylsulfonyl)imide, 1-hexylpyridinium bis(trifluoromethylsulfonyl)imide, 1-octylpyridinium bis(trifluoromethylsulfonyl)imide, 1-hexyl-4-methylpyridinium bis(trifluoromethylsulfonyl)imide, 1-hexyl-4-methylpyridinium hexafluorophosphate, 1-octyl-4- methylpyridinium bis(trifluoromethylsulfonyl)imide, 1-octyl-4-methylpyridinium bis(fluorosulfonyl)imide, 1-methylpyridinium bis(perfluoroethylsulfonyl)imide, and 1-methylpyridinium bis(perfluorobutylsulfonyl)imide ) imide and the like.

Ionic liquids containing ammonium ions include, for example, 1-butyl-3-methylpyridinium bis(trifluoromethanesulfonyl)imide, trimethylheptylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl-N- Propylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl-N-heptylammonium bis(trifluoromethane sulfonyl)imide, and tri-n-butylmethylammoniumbistrifluoromethanesulfonimide.

In addition, commercially available ionic liquids such as pyrrolidinium salts, phosphonium salts, and sulfonium salts can be used as appropriate.

An ionic solid, like an ionic liquid, is a salt of a cation and an anion, but is a substance that exhibits solid properties at 25° C. under normal pressure. Preferred cations include, for example, alkali metal ions, phosphonium ions, pyridinium ions, and ammonium ions.

Examples of ionic solids containing alkali metal ions include lithium bisfluorosulfonylimide, lithium bistrifluoromethylsulfonylimide, lithium bispentafluoroethylsulfonylimide, lithium bisheptafluoropropylsulfonylimide, lithium bisnonanefluorobutylsulfonylimide, sodium bis fluorosulfonylimide, sodium bistrifluoromethylsulfonylimide, sodium bispentafluoroethylsulfonylimide, sodium bisheptafluoropropylsulfonylimide, sodium bisnonanefluorobutylsulfonylimide, potassium bisfluorosulfonylimide, potassium bistrifluoromethylsulfonylimide, potassium bis Pentafluoroethylsulfonylimide, potassium bisheptafluoropropylsulfonylimide, potassium bisnonanefluorobutylsulfonylimide, and the like.

Ionic solids containing phosphonium ions include, for example, tetrabutylphosphonium bisfluorosulfonylimide, tetrabutylphosphonium bistrifluoromethylsulfonylimide, tetrabutylphosphonium bispentafluoroethylsulfonylimide, tetrabutylphosphonium bisheptafluoropropylsulfonylimide, tetrabutylphosphonium bisnonanefluorobutylsulfonylimide, tributylhexadecylphosphonium bisfluorosulfonylimide, tributylhexadecylphosphonium bistrifluoromethylsulfonylimide, tributylhexadecylphosphonium bispentafluoroethylsulfonylimide, tributylhexadecylphosphonium bisheptafluoropropylsulfonylimide, tributylhexa Decylphosphonium bisnonanefluorobutylsulfonylimide, tetraoctylphosphonium bisfluorosulfonylimide, tetraoctylphosphonium bistrifluoromethylsulfonylimide, tetraoctylphosphonium bispentafluoroethylsulfonylimide, tetraoctylphosphonium bisheptafluoropropylsulfonylimide, and tetraoctylphosphonium and bisnonanefluorobutylsulfonylimide.

Examples of ionic solids containing pyridinium ions include 1-hexadecyl-4-methylpyridinium bisfluorosulfonylimide, 1-hexadecyl-4-methylpyridinium bistrifluoromethylsulfonylimide, 1-hexadecyl-4-methylpyridinium bispentafluoroethylsulfonyl imide, 1-hexadecyl-4-methylpyridinium bisheptafluoropropylsulfonylimide, and 1-hexadecyl-4-methylpyridinium bisnonanefluorobutylsulfonylimide.

Examples of ionic solids containing ammonium ions include lauryltrimethylammonium chloride, tributylmethylbistrifluoromethylsulfonylimide, tributylmethylbispentafluoroethylsulfonylimide, tributylmethylbisheptafluoropropylsulfonylimide, tributylmethylmubisnonanefluorobutylsulfonylimide. , octyltributylbistrifluoromethylsulfonylimide, octyltributylbispentafluoroethylsulfonylimide, octyltributylbisheptafluoropropylsulfonylimide, octyltributylbisnonanefluorobutylsulfonylimide, tetrabutylbisfluorosulfonylimide, tetrabutylbistrifluoromethylsulfonylimide imide, tetrabutylbispentafluoroethylsulfonylimide, tetrabutylbisheptafluoropropylsulfonylimide, tetrabutylbisnonanefluorobutylsulfonylimide, and the like.

In addition, known ionic solids whose cations are pyrrolidinium ions, imidazolium ions, sulfonium ions, and the like can be appropriately used.

Surfactants include nonionic surfactants and anionic surfactants, and both types are classified into low-molecular-weight surfactants and high-molecular-weight surfactants.

Examples of nonionic low-molecular-weight surfactants include glycerin fatty acid esters, polyoxyalkylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylamines, polyoxyethylene alkylamine fatty acid esters, and fatty acid diethanolamides. be done.
Anionic low-molecular-weight surfactants include alkylsulfonates, alkylbenzenesulfonates, and alkylphosphates.
Amphoteric low-molecular-weight surfactants include alkylbetaines and alkylimidazolium betaines.

Nonionic polymeric surfactants include polyether ester amide type, ethylene oxide-epichlorohydrin type, and polyether ester type.
Examples of anionic polymeric surfactants include polystyrene sulfonic acid type surfactants.
Examples of amphoteric polymer surfactants include amino acid type amphoteric surfactants such as higher alkylaminopropionates, and betaine type amphoteric surfactants such as higher alkyldimethylbetaines and higher alkyldihydroxyethylbetaines.

The amount of the antistatic agent (AS) added is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass, per 100 parts by mass of the hydroxyl group-terminated urethane prepolymer (UPH).

(leveling agent)
The pressure-sensitive adhesive of the present invention can contain a leveling agent, if desired. By adding a leveling agent, the leveling property of the adhesive layer can be improved. Examples of the leveling agent include acrylic leveling agents, fluorine-based leveling agents, silicone-based leveling agents, and the like. From the viewpoint of suppressing contamination of the adherend after re-peeling of the pressure-sensitive adhesive sheet, acrylic leveling agents and the like are preferable.

The amount of the leveling agent added is not particularly limited, and from the viewpoint of suppressing contamination of the adherend after re-peeling of the adhesive sheet and improving the leveling property of the adhesive layer, it is preferably 0.001 to 2 parts by mass, more preferably 0.01 to 1.5 parts by mass, particularly preferably 0.1 to 1 part by mass.

(other optional ingredients)
The pressure-sensitive adhesive of the present invention can optionally contain other optional components within a range that does not impair the effects of the present invention. Other optional components include catalysts, resins other than urethane-based resins, fillers (talc, calcium carbonate, titanium oxide, etc.), metal powders, coloring agents (pigments, etc.), foil-like materials, softening agents, and electrical conductivity. agents, silane coupling agents, lubricants, corrosion inhibitors, heat stabilizers, weather stabilizers, polymerization inhibitors, antifoaming agents and the like.
When the adhesive of the present invention contains a catalyst, it is preferable to add a known catalytic action inhibitor such as acetylacetone for the purpose of improving the pot life of the adhesive.

(blending ratio)
The pressure-sensitive adhesive of the present invention contains as essential components one or more hydroxyl-terminated urethane prepolymers (UPH) having a specific degree of branching α (UPH), and one or more polyfunctional isocyanate compounds (I), and optionally Contains one or more optional ingredients. The compounding ratio of these components is not particularly limited, but preferred compounding ratios are as follows.
The amount of one or more polyfunctional isocyanate compounds (I) per 100 parts by mass of one or more hydroxyl-terminated urethane prepolymers (UPH) is preferably 1 to 30 parts by mass, more preferably 5 to 25 parts by mass, and particularly preferably is 8 to 20 parts by mass. When the amount of the one or more polyfunctional isocyanate compounds (I) is 1 part by mass or more, the cohesive force of the adhesive layer is good, and when it is 30 parts by mass or less, the pot life is good.

(Method for producing adhesive)
The method for producing the pressure-sensitive adhesive of the present invention is not particularly limited.
One or more hydroxyl-terminated urethane prepolymers (UPH) synthesized by the above method (may be in the form of a solution containing a solvent), one or more polyfunctional isocyanate compounds (I), and if necessary By adding and mixing one or more other optional ingredients, the pressure-sensitive adhesive of the present invention can be produced.

[Adhesive sheet]
The pressure-sensitive adhesive sheet of the present invention includes a base sheet and a pressure-sensitive adhesive layer comprising a cured product of the pressure-sensitive adhesive of the present invention. The adhesive layer can be formed on one side or both sides of the base sheet. If desired, the exposed surface of the adhesive layer can be covered with a release sheet. Note that the release sheet is peeled off before the adhesive sheet is attached to the adherend.

FIG. 1 shows a schematic cross-sectional view of the pressure-sensitive adhesive sheet of the first embodiment according to the present invention. In FIG. 1, reference numeral 10 is an adhesive sheet, reference numeral 11 is a base sheet, reference numeral 12 is an adhesive layer, and reference numeral 13 is a release sheet. The adhesive sheet 10 is a single-sided adhesive sheet in which an adhesive layer is formed on one side of a base sheet.
FIG. 2 shows a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to a second embodiment of the invention. In FIG. 2, reference numeral 20 is an adhesive sheet, reference numeral 21 is a base sheet, reference numerals 22A and 22B are adhesive layers, and reference numerals 23A and 23B are release sheets. The adhesive sheet 20 is a double-sided adhesive sheet in which adhesive layers are formed on both sides of a base sheet.

The base sheet is not particularly limited, and examples thereof include resin sheets, paper, and metal foils. The base sheet may be a laminated sheet in which any one or more layers are laminated on at least one surface of these base sheets. The surface of the base sheet on which the adhesive layer is to be formed may be subjected, if necessary, to an easy-adhesion treatment such as corona discharge treatment and application of an anchor coating agent.

The constituent resin of the resin sheet is not particularly limited, and includes ester resins such as polyethylene terephthalate (PET); olefin resins such as polyethylene (PE) and polypropylene (PP); vinyl resins such as polyvinyl chloride; Amide-based resins; urethane-based resins (including foams); combinations thereof, and the like.
The thickness of the resin sheet other than the polyurethane sheet is not particularly limited, preferably 15 to 300 μm. The thickness of the polyurethane sheet (including foam) is not particularly limited, preferably 20 to 50,000 μm.

The paper is not particularly limited, and includes plain paper, coated paper, art paper, and the like.
The constituent metal of the metal foil is not particularly limited, and examples thereof include aluminum, copper, and combinations thereof.

The release sheet is not particularly limited, and a known release sheet obtained by applying a known release treatment such as coating of a release agent to the surface of a base sheet such as a resin sheet or paper can be used.

[Method for producing adhesive sheet]
A pressure-sensitive adhesive sheet can be produced by a known method.
First, the pressure-sensitive adhesive of the present invention is applied to the surface of a substrate sheet to form a coating layer comprising the pressure-sensitive adhesive of the present invention. A known method can be applied as the coating method, and examples thereof include a roll coater method, a comma coater method, a die coater method, a reverse coater method, a silk screen method, and a gravure coater method.
Next, the coating layer is dried and cured to form an adhesive layer composed of the cured adhesive of the present invention. The heat drying temperature is not particularly limited, and is preferably about 60 to 150°C. The thickness of the adhesive layer (thickness after drying) varies depending on the application, but is preferably 0.1 to 200 μm.
Next, if necessary, a release sheet is attached to the exposed surface of the adhesive layer by a known method.
A single-sided pressure-sensitive adhesive sheet can be produced in the manner described above.
A double-sided pressure-sensitive adhesive sheet can be produced by performing the above operation on both sides.

Contrary to the above method, the pressure-sensitive adhesive of the present invention is applied to the surface of a release sheet to form a coating layer comprising the pressure-sensitive adhesive of the present invention, and then the coating layer is dried and cured to obtain the adhesive of the present invention. An adhesive layer made of a cured product of the adhesive may be formed, and a substrate sheet may be laminated on the exposed surface of the adhesive layer.

The method for producing an adhesive sheet preferably includes a coating step of applying an adhesive onto a base sheet, and heating to form an adhesive layer containing a cured product of the adhesive by heating and drying the formed coating layer. a winding step of winding the obtained adhesive sheet around a core to form an adhesive sheet roll; and a curing step of curing the adhesive sheet roll.

As described above, according to the present invention, the adhesive layer has good initial curability, suppresses an increase in adhesive strength even when exposed to a heat environment, especially a moist heat environment, and has good removability. It is possible to provide a pressure-sensitive adhesive capable of forming and a pressure-sensitive adhesive sheet using the same.
According to the first embodiment of the present invention, the initial curability and the removability (effect of suppressing the increase in adhesive strength) when exposed to a thermal environment, particularly a hot and humid environment, are good. A pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer with good adhesion, scratch resistance, and adhesion to curved surfaces, and a pressure-sensitive adhesive sheet using the same can be provided.
According to the second embodiment of the present invention, the initial curability and the removability (effect of suppressing the increase in adhesive strength) when exposed to a thermal environment, particularly a hot and humid environment, are good, and the folding resistance is good. It is possible to provide a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer having good toughness, cuttability, and heat resistance, and a pressure-sensitive adhesive sheet using the same.

[Use]
The pressure-sensitive adhesive sheet of the present invention can be used in the form of tapes, labels, stickers, double-sided tapes, and the like. The pressure-sensitive adhesive sheet of the present invention is suitable for use as a surface protection sheet, a cosmetic sheet, an anti-slip sheet, and the like.
In this specification, "sheet" includes "film" and "tape" unless otherwise specified.
Flat panel displays such as liquid crystal displays (LCDs) and organic electroluminescent displays (OELDs), as well as touch panel displays combining such flat panel displays and touch panels, are widely used in televisions (TVs), personal computers (PCs), mobile phones, and widely used in electronic devices such as personal digital assistants.
The pressure-sensitive adhesive sheet of the present invention can be used for flat panel displays and touch panel displays (these are also collectively referred to simply as "displays"), substrates manufactured or used in these manufacturing processes (glass substrates, and ITO on glass substrates). (Indium Tin Oxide) film-formed ITO/glass substrate, etc.) and as a surface protective sheet for optical members and the like.

Synthesis examples, examples according to the present invention, and comparative examples are described below. In the description below, unless otherwise specified, "parts" means parts by mass, "%" means % by mass, and "RH" means relative humidity. Unless otherwise specified, the unit of the compounding amount in the table is "mass part". Unless otherwise specified, the amount of components other than the solvent is the non-volatile content conversion value.

[Evaluation items and evaluation methods for materials or hydroxyl-terminated urethane prepolymers]
Evaluation items and evaluation methods for materials or hydroxyl-terminated urethane prepolymers are as follows.
(Mw, Mn)
Weight average molecular weight (Mw) and number average molecular weight (Mn) were measured by gel permeation chromatography (GPC) method. The measurement conditions are as follows. Both Mw and Mn are polystyrene equivalent values.
Apparatus: SHIMADZU Prominence (manufactured by Shimadzu Corporation),
Column: SHODEX L
Three F-804 (manufactured by Showa Denko KK) are connected in series,
Detector: Differential Refractive Index Detector,
solvent: tetrahydrofuran (THF),
flow rate: 1 mL/min,
Solvent temperature: 40°C,
Sample concentration: 0.2%,
Sample injection volume: 200 μL.

(Degree of branching α)
The degree of branching α was measured using an apparatus (GPC-MALS-VISCO) in which a multi-angle light scattering detector (MALS) and a viscosity detector (VISCO) were combined with a gel permeation chromatograph (GPC).

(Viscosity of hydroxyl-terminated urethane prepolymer solution)
The viscosity of the hydroxyl-terminated urethane prepolymer solution at 25° C. was measured immediately after preparation by placing it in a glass bottle with a lid and immersing it in a constant temperature water bath at 25° C. One hour later, the viscosity was measured. The viscosity was measured using a B-type viscometer ("TVB10 viscometer" manufactured by Toki Sangyo Co., Ltd.).

(Nonvolatile content)
The non-volatile content of the solution of the hydroxyl group-terminated urethane prepolymer was determined from the change in mass after drying after drying an approximately 1 g sample by heating at 120° C. for 20 minutes.

[Synthesis example of polyol]
(Synthesis Example Z-1)
An autoclave equipped with a stirring device and a temperature control device was charged with 100.0 parts of butylethylpropanediol (BEPD) as the first component and 4.0 parts of potassium hydroxide, heated to 100° C., and stirred. 150.0 parts of propylene oxide (PO) as the second component was continuously added at the bottom.
To the resulting reaction product, 40.0 parts of water and 40.0 parts of an alkali adsorbent "Kyoward 600" (manufactured by Kyowa Chemical Industry Co., Ltd.) were added, and the mixture was stirred and mixed at 90°C for 1 hour. . After that, the added alkali adsorbent was removed using a filter covered with filter paper. The reaction product passed through the filter paper was dehydrated under the conditions of 130° C. and pressure of 2.7 kPa.
As described above, a polyether polyol (HX-1) having a number average molecular weight (Mn) of 400, an average functional group number of secondary, and a branching degree α of 0.45 was obtained. Tables 1-1 and 1-2 show the composition of raw materials and the types and properties of the obtained polyols.

(Synthesis Examples Z-3, Z-11)
A polyol was obtained in the same manner as in Synthesis Example Z-1, except that the types and amounts of the first and second components were changed. Tables 1-1 and 1-2 show the composition of raw materials and the types and properties of the obtained polyols.

(Synthesis Example Z-2)
100 parts of terephthalic acid (TPA) as the first component, 27 parts of trimethylolpropane (TMP) as the second component, and 1,9- 74 parts of nonanediol (ND) were charged. The mixture was heated to 200° C. in a nitrogen atmosphere at normal pressure, and an esterification reaction was carried out while distilling out the produced water from the system. 0.01 part of tetraisopropyl titanate was added when the distillate of the generated water was reduced, and the reaction was continued while reducing the pressure with a vacuum pump. A polyester polyol (HX-2) having a branching degree α of 0.35 was obtained.

(Synthesis Examples Z-7, Z-10, Z-16)
A polyol was obtained in the same manner as in Synthesis Example Z-2 except that the types and amounts of the first, second and third components were changed. Tables 1-1 and 1-2 show the composition of raw materials and the types and properties of the obtained polyols.

(Synthesis Example Z-4)
An autoclave equipped with a stirring device and a temperature control device was charged with 100.0 parts of glycerin as the first component and 4.0 parts of potassium hydroxide, heated to 100 ° C., and stirred as the second component. 334 parts of 1,2-butylene oxide (1,2-BO) were continuously added.
To the resulting reaction product, 40.0 parts of water and 40.0 parts of an alkali adsorbent "Kyoward 600" (manufactured by Kyowa Chemical Industry Co., Ltd.) were added, and the mixture was stirred and mixed at 90°C for 1 hour. . After that, the added alkali adsorbent was removed using a filter covered with filter paper. The reaction product passed through the filter paper was dehydrated under the conditions of 130° C. and pressure of 2.7 kPa.
An autoclave equipped with a stirring device and a temperature control device was charged with the above reaction product, and further charged with 0.10 parts of zinc hexacyanocobaltate catalyst, then the temperature in the reactor was raised to 130° C., and under stirring, 282 parts of 1,2-butylene oxide (1,2-BO) (10% by mass of the total amount used) was added as the third component.
After reacting for 2 hours and activating the catalyst, 2538 parts of 1,2-butylene oxide (1,2-BO) as the third component (90% by mass of the total amount used) was added continuously under conditions of 100 ° C. was added gradually and mixed and stirred at 95° C. until the pressure was constant. The resulting mixture was vacuum stripped at 100° C. for 0.5 hours to remove unreacted third component from the reactor.
As described above, a polyether polyol (HX-S-2) having a number average molecular weight (Mn) of 3000, an average functional group number of secondary and a branching degree α of 0.05 was obtained. Tables 1-1 and 1-2 show the raw material composition and the properties of the resulting polyol.

(Synthesis Examples Z-5, Z-6, Z-9, Z-12 to Z-15)
A polyol was obtained in the same manner as in Synthesis Example Z-4, except that the types and amounts of the first, second and third components were changed. Tables 1-1 and 1-2 show the composition of raw materials and the types and properties of the obtained polyols.

(Synthesis Example Z-8)
A round bottom flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, and a condenser was charged with 1854 g of polycarbonate diol (manufactured by Daicel Chemical Industries, Ltd.; trade name: CD220, molecular weight: 2011, hydroxyl value: 55.8), 21 g of trimethylolpropane, 126 g of pentaerythritol and 0.08 g of tetrabutyl titanate as a catalyst were charged. The mixture was heated under normal pressure while stirring. The reaction temperature was gradually raised to reach 220° C., and then the temperature was maintained for 8 hours to carry out the reaction.
Samples were taken at any time during the reaction, and the remaining diol component (here, 1,6-hexanediol) and triol component (here, trimethylolpropane) were quantified by gas chromatography analysis, and the transesterification reaction reached equilibrium. After confirming that the reaction was complete, the reaction was terminated.
As described above, a polycarbonate polyol (HX-S-6) having a number average molecular weight (Mn) of 1000, an average functional group number of primary and a branching degree α of 0.05 was obtained. Tables 1-1 and 1-2 show the composition of raw materials and the types and properties of the obtained polyols.

Each abbreviation in Tables 1-1 and 1-2 indicates the following compounds.
BEPD: butyl ethyl propanediol,
TPA: terephthalic acid,
AA: adipic acid,
PG: propylene glycol,
IPA: isophthalic acid,
PO: propylene oxide,
TMP: trimethylolpropane,
1,2-BO: 1,2-butylene oxide,
EO: ethylene oxide,
THF: tetrahydrofuran,
PD-9: 2,4-diethyl-1,5-pentanediol,
ND: 1,9-nonanediol,
MPD: 2-methylpentane-2,4-diol,
CD220: polycarbonate diol (manufactured by Daicel Chemical Industries, Ltd.: trade name CD220, molecular weight 2011, hydroxyl value 55.8),
PET: pentaerythritol.

[material]
The materials used are as follows.
Table 1-2 shows the type, functional group number, Mn, average functional group series, and branching degree α of the active hydrogen group-containing compounds (HX) and (HY) used. The type, number of functional groups, and Mn of the polyisocyanate (N) used are shown in Table 1-2.

<Active hydrogen group-containing compound (HX)>
(HX-1): Polyether polyol.
(HX-2): polyester polyol.
(HX-S-1): Polycaprolactone polyol.
(HX-S-2): Polyether polyol.
(HX-S-3): Polyether polyol.
(HX-S-4): Polyether polyol.
(HX-S-5): polyester polyol.
(HX-S-6): polycarbonate polyol.
(HX-S-7): Polyether polyol, "DK Polyol G480" manufactured by Daiichi Kogyo Seiyaku.
(HX-S-8): Polyether polyol, "ADEKA Polyether AM-302" manufactured by ADEKA.

<Active hydrogen group-containing compound (HY)>
(HY-1): Polyether polyol.
(HY-2): polyester polyol.
(HY-L-1): Polyether polyol.
(HY-L-2): Polyether polyol.
(HY-L-3): Polyether polyol.
(HY-L-4): Polyether polyol.
(HY-L-5): Polyether polyol.
(HY-L-6): polyester polyol.
(HY-L-7): Polyether polyol, "Poly Hardener D-100A" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.
(HY-L-8): Polyester polyol, "Kuraray Polyol P-1010" manufactured by Kuraray Co., Ltd.
(HY-L-9): Polyether polyol, "Poly Hardener D-40" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

<Polyisocyanate (N)>
(N-1): HDI, hexamethylene diisocyanate, Desmodur H manufactured by Sumika Covestrourethane.
(N-2): IPDI, isophorone diisocyanate, manufactured by Sumika Covestro Urethane Co., Ltd., Desmodur I.
(N-3): TDI, tolylene diisocyanate (a mixture of 2,4-tolylene diisocyanate (80% by mass) and 2,6-tolylene diisocyanate (20% by mass)), manufactured by Tosoh Corporation, Coronate T-80 .
(N-4): HDI Nurate, Sumidule N-3300, manufactured by Sumika Bayer Urethane Co., Ltd., hexamethylene diisocyanate (HDI)/isocyanurate.

<Polyfunctional isocyanate compound (I)>
(I-1) HDI adduct, Coronate HL, manufactured by Tosoh Corporation, hexamethylene diisocyanate (HDI)/trimethylolpropane (TMP) adduct.
(I-2) HDI nurate, Sumidur N-3300, manufactured by Sumika Bayer Urethane Co., Ltd., hexamethylene diisocyanate (HDI)/isocyanurate.

<Antioxidant (O)>
(O-1): IRGANOX 1010, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], phenolic antioxidant, manufactured by BASF.

<Plasticizer (P)>
(P-1): ADEKA CIZER RS700, polyether ester plasticizer, manufactured by ADEKA.
(P-2): Excepar MOL, methyl oleate, manufactured by Kao Corporation.

<Antistatic agent (AS)>
(AS-1): ionic liquid, tri-n-butylmethylammonium bistrifluoromethanesulfonimide.

[Synthesis Example of Solution of Hydroxyl Group-Terminated Urethane Prepolymer (UPH)]
(Synthesis Example 1) One-step dropping method (Method 1)
In a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, a thermometer, and a dropping funnel, 80.0 parts by mass of the active hydrogen group-containing compound (HX-S-1) and the active hydrogen group-containing compound ( 20.0 parts by mass of HY-L-5), 42.8 parts by mass of toluene, and 0.020 parts by mass of dioctyltin dilaurate as a catalyst and 0.008 parts by mass of tin 2-ethylhexanoate were charged and mixed. After that, the content liquid was gradually heated to 80°C.
25.0 parts by mass of polyisocyanate (N-1) and 24.5 parts by mass of toluene were charged into the dropping funnel and mixed, and this mixed solution was added dropwise to the four-necked flask over 1 hour. After the dropwise addition was completed, the mixture was allowed to react for 1 hour.
The ratio of the number of moles of isocyanate groups in the polyisocyanate (N) used in the reaction to the total number of moles of active hydrogen groups in all active hydrogen group-containing compounds (H) used in the reaction (NCO/H ratio) is was 0.78.
After confirming the disappearance of the remaining isocyanate groups by infrared spectroscopic analysis (IR analysis), the content liquid was cooled to 40° C. to complete the reaction. Finally, 0.56 parts by mass of acetylacetone was added.
As described above, a solution of a colorless and transparent hydroxyl group-terminated urethane prepolymer (UPH-1) having a non-volatile content of 65% and a viscosity of 3200 cps was obtained. Table 2-1 shows the main compounding compositions, the NCO/H ratio, and the Mw, Mn and branching degree α of the obtained hydroxyl group-terminated urethane prepolymer. In each example of Tables 2-1, 2-2, 3-1, 3-2, and 4, conditions not described in the tables were common conditions.

(Synthesis Examples 2-14, 19-33) One-step dropping method (Method 1)
In Synthesis Examples 2 to 14 and 19 to 33, colorless materials were obtained in the same manner as in Synthesis Example 1 except that the type of active hydrogen group-containing compound (H), the type of polyisocyanate (N), and the blending ratio thereof were changed. Solutions of transparent hydroxyl-terminated urethane prepolymers (UPH-2) to (UPH-14) and (UPH-19) to (UPH-33) were obtained. In each synthesis example, the main compounding composition, NCO/H ratio, and Mw, Mn, and branching degree α of the obtained hydroxyl-terminated urethane prepolymer are shown in Tables 2-1, 2-2, 3-1, and 3-1. 3-2.

(Synthesis Example 15) Batch preparation method (Method 2)
32.0 parts by mass of active hydrogen group-containing compound (HX-S-7) and active hydrogen group-containing compound ( HY-L-7) 68.0 parts by mass, polyisocyanate (N-1) 26.0 parts by mass, toluene 67.8 parts by mass, and dioctyltin dilaurate 0.020 parts by mass as a catalyst were charged and mixed. . After that, the content liquid was heated to 80° C. and reacted for 3 hours.
The ratio of the number of moles of isocyanate groups in the polyisocyanate (N) used in the reaction to the total number of moles of active hydrogen groups in all active hydrogen group-containing compounds (H) used in the reaction (NCO/H ratio) is was 0.75.
After confirming the disappearance of the remaining isocyanate groups by infrared spectroscopic analysis (IR analysis), the content liquid was cooled to 40° C. to complete the reaction. Finally, 0.56 parts by mass of acetylacetone was added.
As described above, a solution of a colorless and transparent hydroxyl group-terminated urethane prepolymer (UPH-15) having a non-volatile content of 65% and a viscosity of 1800 cps was obtained. Table 2-2 shows the main compounding compositions, the NCO/H ratio, and the Mw, Mn and branching degree α of the obtained hydroxyl group-terminated urethane prepolymer.

(Synthesis Examples 16 and 34) Batch preparation method (Method 2)
In Synthesis Examples 16 and 34, the same procedure as in Synthesis Example 15 was carried out, except that the type of active hydrogen group-containing compound (H), the type of polyisocyanate (N), and the blending ratio thereof were changed, to produce colorless and transparent hydroxyl group-terminated Solutions of urethane prepolymers (UPH-16) and (UPH-34) were obtained. Tables 2-2 and 3-2 show the main compounding composition, NCO/H ratio, Mw, Mn, and degree of branching α of the obtained hydroxyl-terminated urethane prepolymers in each synthesis example.

(Synthesis Examples 41 and 42) Batch preparation method (Method 2)
In Synthesis Examples 41 and 42, the same procedure as in Synthesis Example 14 was performed except that the type of active hydrogen group-containing compound (H), the type of polyisocyanate (N), and the blending ratio thereof were changed. of hydroxyl group-terminated urethane prepolymers (UPC-41) and (UPC-42) were obtained. Table 4 shows the main compounding composition, the NCO/H ratio, and the Mw, Mn and branching degree α of the obtained hydroxyl group-terminated urethane prepolymer in each synthesis example.

(Synthesis Example 17) Two-step reaction method (Method 3)
80.0 parts by mass of active hydrogen group-containing compound (HX-S-2) and 50.5 parts by mass of toluene were placed in a four-necked flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel. , 0.020 parts by mass of dioctyltin dilaurate and 0.008 parts by mass of tin 2-ethylhexanoate as catalysts were charged and mixed. After that, the content liquid was gradually heated to 80°C.
4.0 parts by mass of polyisocyanate (N-1) and 4.0 parts by mass of toluene were charged into a dropping funnel and mixed, and this mixed solution was added dropwise to the four-necked flask over 1 hour. After the dropwise addition was completed, the mixture was allowed to react for 1 hour.
After confirming the disappearance of the residual isocyanate groups by infrared spectroscopic analysis (IR analysis), the content liquid was cooled to 60° C. or lower. After 20.0 parts by mass of the active hydrogen group-containing compound (HY-L-6) was added to the content liquid and mixed, the temperature of the content liquid was gradually raised to 80°C.
1.5 parts by mass of polyisocyanate (N-1) and 3.0 parts by mass of toluene were charged into a dropping funnel and mixed, and this mixed solution was added dropwise to the four-necked flask over 1 hour. After the dropwise addition was completed, the mixture was allowed to react for 1 hour.
The ratio of the number of moles of isocyanate groups in the polyisocyanate (N) used in the reaction to the total number of moles of active hydrogen groups in all active hydrogen group-containing compounds (H) used in the reaction (NCO/H ratio) is was 0.65.
After confirming the disappearance of the remaining isocyanate groups by infrared spectroscopic analysis (IR analysis), the content liquid was cooled to 40° C. to terminate the reaction. Finally, 0.46 parts by mass of acetylacetone was added.
As described above, a solution of a colorless and transparent hydroxyl group-terminated urethane prepolymer (UPH-17) having a non-volatile content of 65% and a viscosity of 7000 cps was obtained. Table 2-2 shows the main compounding compositions, the NCO/H ratio, and the Mw, Mn and branching degree α of the obtained hydroxyl group-terminated urethane prepolymer.

(Synthesis Example 35) Two-step reaction method (Method 3)
In Synthesis Example 35, the same procedure as in Synthesis Example 17 was performed except that the type of active hydrogen group-containing compound (H), the type of polyisocyanate (N), and the blending ratio thereof were changed, to prepare a colorless and transparent hydroxyl group-terminated urethane resin. A solution of polymer (UPH-35) was obtained. Table 3-2 shows the main compounding compositions, the NCO/H ratio, and the Mw, Mn and branching degree α of the obtained hydroxyl group-terminated urethane prepolymer.

(Synthesis Example 18) Two-step reaction method (Method 4)
20.0 parts by mass of an active hydrogen group-containing compound (HY-L-6) and 50.5 parts by mass of toluene were placed in a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, a thermometer, and a dropping funnel. , 0.020 parts by mass of dioctyltin dilaurate and 0.008 parts by mass of tin 2-ethylhexanoate as catalysts were charged and mixed. After that, the content liquid was gradually heated to 80°C.
1.5 parts by mass of polyisocyanate (N-1) and 3.0 parts by mass of toluene were charged into a dropping funnel and mixed, and this mixed solution was added dropwise to the four-necked flask over 1 hour. After the dropwise addition was completed, the mixture was allowed to react for 1 hour.
After confirming the disappearance of the residual isocyanate groups by infrared spectroscopic analysis (IR analysis), the content liquid was cooled to 60° C. or lower. 80.0 parts by mass of the active hydrogen group-containing compound (HX-S-2) was added to and mixed with the content liquid, and the temperature of the content liquid was gradually raised to 80°C.
4.0 parts by mass of polyisocyanate (N-1) and 4.0 parts by mass of toluene were charged into a dropping funnel and mixed, and this mixed solution was added dropwise to the four-necked flask over 1 hour. After the dropwise addition was completed, the mixture was allowed to react for 1 hour.
The ratio of the number of moles of isocyanate groups in the polyisocyanate (N) used in the reaction to the total number of moles of active hydrogen groups in all active hydrogen group-containing compounds (H) used in the reaction (NCO/H ratio) is was 0.65.
After confirming the disappearance of the remaining isocyanate groups by infrared spectroscopic analysis (IR analysis), the content liquid was cooled to 40° C. to complete the reaction. Finally, 0.46 parts by mass of acetylacetone was added.
As described above, a solution of a colorless and transparent hydroxyl group-terminated urethane prepolymer (UPH-18) having a non-volatile content of 65% and a viscosity of 2800 cps was obtained. Table 2-2 shows the main compounding compositions, the NCO/H ratio, and the Mw, Mn and branching degree α of the obtained hydroxyl group-terminated urethane prepolymer.

(Synthesis Example 36) Two-step reaction method (Method 4)
In Synthesis Example 36, the same procedure as in Synthesis Example 18 was carried out, except that the type of active hydrogen group-containing compound (H), the type of polyisocyanate (N), and the blending ratio thereof were changed, to prepare a colorless and transparent hydroxyl group-terminated urethane resin. A solution of polymer (UPH-36) was obtained. Table 3-2 shows the main compounding compositions, the NCO/H ratio, and the Mw, Mn and branching degree α of the obtained hydroxyl group-terminated urethane prepolymer.

[Manufacturing of adhesive and adhesive sheet]
(Example 1)
100 parts by mass of the solution of the hydroxyl group-terminated urethane prepolymer (UPH-1) obtained in Synthesis Example 1, 15 parts by mass of the polyfunctional isocyanate compound (I-1), and 1 part by mass of the antioxidant (O-1). , 15 parts by mass of the plasticizer (P-1) and 100 parts by mass of ethyl acetate as a solvent were blended and stirred with a disper to obtain a urethane adhesive. In addition, the amount of each material used other than the solvent indicates a non-volatile content conversion value (the same applies to other examples and comparative examples). Table 5 shows the main compounding composition.

A polyethylene terephthalate film (PET film, Lumirror T-60: manufactured by Toray Industries, Inc.) having a thickness of 50 μm was prepared as a base sheet. The obtained adhesive was coated on one side of this base sheet so that the thickness of the adhesive layer after drying was 12 μm, and dried at 100° C. for 2 minutes to form an adhesive layer. A release sheet having a thickness of 38 μm (Superstick SP-PET38: manufactured by Lintec) was adhered to the adhesive layer to obtain an adhesive sheet. After curing for 1 week at 23° C.-50% RH, various evaluations were made.

(Examples 2 to 57, Comparative Examples 1 and 2)
In each of Examples 2 to 57 and Comparative Examples 1 and 2, a urethane-based pressure-sensitive adhesive and its A pressure-sensitive adhesive sheet was produced using In each example of Tables 5 and 7, conditions not described in the tables were common conditions.

[Evaluation items and evaluation methods for adhesive sheets]
Evaluation items and evaluation methods of the adhesive sheet are as follows.

(Substrate adhesion)
The adhesive layer of the obtained adhesive sheet was half-cut 11 times at intervals of 1 mm in two straight directions orthogonal to each other to form 100 squares of 1 mm square. After rubbing the entire 100 squares with a finger back and forth 20 times, the number of squares remaining on the base sheet was visually counted. Evaluation criteria are as follows.
A: The number of remaining cells is 71 to 100, excellent.
◯: 51 to 70 remaining squares, good.
Δ: 21 to 50 remaining squares, practically acceptable.
x: 0 to 20 remaining squares, impractical.

(initial curability)
A release sheet was peeled off from the resulting adhesive sheet. The exposed surface of the adhesive layer was rubbed with a fingertip, and the presence or absence of adhesion of the components of the adhesive layer to the fingertip and the presence or absence of rubbed marks on the surface of the adhesive layer were visually observed. Evaluation criteria are as follows.
⊚: Excellent, no component of the adhesive layer adhered to the fingertips and no trace of rubbing remained on the surface of the adhesive layer.
◯: The components of the adhesive layer did not adhere to the fingertips, but the surface of the adhesive layer left a slight rubbing mark, which was good.
Δ: Components of the adhesive layer slightly adhered to the fingertips, giving a tacky feel and leaving a slight rubbing mark on the surface of the adhesive layer, practically acceptable.
x: The components of the adhesive layer adhered to the fingertips remarkably, giving a sticky feeling and rubbing traces remaining on the surface of the adhesive layer, impractical.

(Scratch resistance)
A release sheet was peeled off from the resulting adhesive sheet. The tip (pen tip) of a POM pen (pen tip diameter: 0.8 mm) inclined at an angle of 45° was brought into contact with the exposed surface of the adhesive layer. While maintaining this state, the pen tip was horizontally moved about 10 cm so as to draw a straight line. The position was changed and the same operation was performed at a total of 10 locations. Each location was visually observed for the presence or absence of scratches, and the number of locations where scratches were formed was determined. Visual observation was performed under a fluorescent lamp. Evaluation criteria are as follows.
⊚: Excellent with no damage.
◯: Scratches in 1 to 2 places, good.
Δ: Scratches at 3 to 5 locations, practically acceptable.
x: Scratches at 6 or more locations, impractical.

(Curved surface adhesion)
A test piece having a width of 25 mm and a length of 40 mm was cut out from the obtained adhesive sheet. Next, in an atmosphere of 23 ° C.-50% RH, the release sheet is peeled off from the test piece, and the exposed adhesive layer is attached along the peripheral surface of a polypropylene cylinder (diameter 30 mmφ, height 300 mm). rice field. At this time, the width direction of the test piece was aligned with the height direction of the cylindrical body. After this sample was left in an atmosphere of 23° C.-50% RH for 3 days, the degree of adhesion of the test piece to the cylindrical body was visually observed. Evaluation criteria are as follows.
◯: Good, no lifting at the edge of the test piece.
Δ: The edge of the test piece is lifted, and the width of the peeled portion is 1 mm or more and less than 3 mm, practically acceptable.
x: The edge of the test piece was lifted, and the peeled portion had a width of 3 mm or more, impractical.

(Removability (60° C.-90% RH, 24 hours))
A test piece having a width of 25 mm and a length of 100 mm was cut out from the obtained adhesive sheet. Then, in an atmosphere of 23° C.-50% RH, the release sheet was peeled off from the test piece, and the exposed adhesive layer was adhered to a caustic soda glass plate and crimped by reciprocating a 2 kg roll once over the test piece. Then, it was left in an atmosphere of 60° C.-90% RH for 24 hours and air-cooled in an atmosphere of 23° C.-50% RH for 30 minutes. Then, according to JIS Z 0237, using a tensile tester (Tensilon: manufactured by Orientec), the adhesive strength was measured under the conditions of a peel speed of 300 mm/min and a peel angle of 180°. The lower the adhesive strength, the easier it is to re-peel. Evaluation criteria are as follows.
A: Less than 50 mN/25 mm, excellent.
○: 50 mN/25 mm or more and less than 100 mN/25 mm, good.
Δ: 100 mN/25 mm or more and less than 300 mN/25 mm, practically acceptable.
×: more than 300 mN/25 mm, impractical.

(Folding resistance)
A test piece having a width of 25 mm and a length of 40 mm was cut out from the obtained adhesive sheet. Next, in an atmosphere of 60 ° C., peel off the release sheet from the test piece, attach about half of the exposed adhesive layer in the length direction to a 10 mm thick caustic soda glass plate, and fold the rest in the 180 ° direction. pasted. It was left in an atmosphere of 60°C for 3 days. After that, the degree of adhesion to the caustic soda glass plate was visually observed for the bent portion and the edge of the portion where the test piece was attached. Evaluation criteria are as follows.
⊚: Excellent with no lifting at the bent portion and the end portion.
○: There is a float at the bent portion and / or the edge, the width of the peeled portion is less than 1 mm, good △: There is a float at the bent portion and / or the edge, the width of the peeled portion is 1 mm or more and less than 3 mm, practical Yes.
x: The folded part and/or the end part is lifted, and the peeled part has a width of 3 mm or more, which is not practical.

(Cutability)
A 100 mm square test piece was cut out from the resulting pressure-sensitive adhesive sheet. As a punching machine, an SA1008 compact punching machine type III (manufactured by Tester Sangyo Co., Ltd.) was prepared. A circular Thomson blade with a diameter of 10 mm was used to continuously perform 50 shots of punching, and the cutability was evaluated. Evaluation criteria are as follows.
⊚: Excellent because adhesive components do not adhere to the blade and the release sheet can be cleanly peeled off from the punched circular adhesive sheet with a light force.
◯: Although the adhesive component slightly adheres to the blade, the release sheet can be cleanly peeled off from the punched circular adhesive sheet with a light force, which is good.
Δ: A small amount of the adhesive component adheres to the blade, or there is a little resistance when peeling the release sheet from the punched circular adhesive sheet, which is practically acceptable.
Poor: The adhesive component adheres to the blade remarkably, or resistance is high when peeling off the release sheet from the punched circular adhesive sheet, impractical.

(Heat resistance (150°C, 1 hour))
A test piece having a width of 25 mm and a length of 100 mm was cut out from the obtained adhesive sheet. Then, in an atmosphere of 23° C.-50% RH, the release sheet was peeled off from the test piece, and the exposed adhesive layer was adhered to a caustic soda glass plate and crimped by reciprocating a 2 kg roll once over the test piece. Then, it was left in an atmosphere of 150° C. for 1 hour and air-cooled in an atmosphere of 23° C.-50% RH for 30 minutes. Then, according to JIS Z 0237, using a tensile tester (Tensilon: manufactured by Orientec), the adhesive strength was measured under the conditions of a peel speed of 300 mm/min and a peel angle of 180°. The lower the adhesive strength, the easier it is to re-peel. Evaluation criteria are as follows.
A: Less than 500 mN/25 mm, excellent.
○: 500 mN/25 mm or more and less than 1000 mN/25 mm, good.
Δ: 1000 mN/25 mm or more and less than 3000 mN/25 mm, practically acceptable.
×: more than 3000 mN/25 mm, impractical.

[Evaluation results]
Tables 6 and 8 show the evaluation results.
In Synthesis Examples 1 to 36, one type containing an active hydrogen group-containing compound (HX) having a branching degree α of 0.5 or less and/or an active hydrogen group-containing compound (HY) having a branching degree α of greater than 0.5 Using the above active hydrogen group-containing compound (H) and polyisocyanate (N), hydroxyl group-terminated urethane prepolymers (UPH-1) to (UPH-36) having a branching degree α of 0.2 to 0.8 ).
In Examples 1 to 57 using hydroxyl group-terminated urethane prepolymers (UPH-1) to (UPH-36) having a branching degree α of 0.2 to 0.8, the obtained pressure-sensitive adhesive sheets exhibited initial curability and The evaluation result of removability (60° C.-90% RH) was good. The evaluation results for the other evaluation items were also good.

In Synthesis Examples 1 to 13, 16, and 17, at least one active hydrogen group-containing compound (H) contains 50% by mass or more of an active hydrogen group-containing compound (HX) having a branching degree α of 0.5 or less, The hydroxyl group-terminated urethane prepolymer (UPH) had a branching degree α of 0.2 to 0.6. The pressure-sensitive adhesive sheets obtained in Examples 1 to 22, 25, and 26 using the hydroxyl-terminated urethane prepolymers (UPH) obtained in these Synthesis Examples had initial curability and were exposed to a thermal environment, particularly a moist and hot environment. The removability (the effect of suppressing an increase in adhesive strength) was good, and the adhesiveness to the substrate, the scratch resistance, and the adhesiveness to the curved surface were also good.

In Synthesis Examples 19 to 29, 31, 33, and 36, at least one active hydrogen group-containing compound (H) contains 50% by mass or more of an active hydrogen group-containing compound (HY) having a branching degree α of more than 0.5. Including, the hydroxyl group-terminated urethane prepolymer (UPH) had a branching degree α of more than 0.6 and 0.8 or less. The pressure-sensitive adhesive sheets obtained in Examples 28 to 46, 48, 50, and 53 using the hydroxyl group-terminated urethane prepolymers (UPH) obtained in these Synthesis Examples have excellent initial curability and resistance to heat environments, particularly wet heat environments. Good removability (effect of suppressing increase in adhesive strength) when exposed to light, and also good folding endurance, cutting property, and heat resistance.

In Synthesis Example 41, an active hydrogen group-containing compound (HX) having a branching degree α of 0.5 or less and a polyisocyanate (N) were used to prepare a comparative hydroxyl group terminal having a branching degree α of less than 0.2. A urethane prepolymer (UPC-1) was obtained.
In Synthesis Example 42, an active hydrogen group-containing compound (HY) having a branching degree α of more than 0.5 and a polyisocyanate (N) were used to prepare a comparative hydroxyl group-terminated compound having a branching degree α of more than 0.8. A urethane prepolymer (UPC-2) was obtained.
In Comparative Examples 1 and 2 using the hydroxyl group-terminated urethane prepolymer (UPC-1) or (UPC-2) for comparison, the obtained pressure-sensitive adhesive sheets exhibited excellent initial curing and removability (60° C.-90% RH ) was poor. Evaluation results were also poor for many other evaluation items.

The present invention is not limited to the above-described embodiments and examples, and design changes are possible as appropriate without departing from the gist of the present invention.

10, 20 adhesive sheets 11, 21 base sheet 12, 22A, 22B adhesive layer 13, 23A, 23B release sheet

Claims (8)

a hydroxyl group-terminated urethane prepolymer (UPH) which is a reaction product of one or more active hydrogen group-containing compounds (H) having a plurality of active hydrogen groups in one molecule and one or more polyisocyanates (N);
A pressure-sensitive adhesive containing a polyfunctional isocyanate compound (I),
One or more active hydrogen group-containing compounds (H) contain 70% by mass or more of active hydrogen group-containing compounds (HY) having a degree of branching of more than 0.5 as measured by GPC-MALS,
A pressure-sensitive adhesive in which the hydroxyl group-terminated urethane prepolymer (UPH) has a degree of branching of more than 0.6 and not more than 0.8 as measured by the GPC-MALS method. 2. The pressure-sensitive adhesive according to claim 1, wherein the hydroxyl group -terminated urethane prepolymer (UPH) has a branching degree of 0.7 to 0.8 as measured by the GPC-MALS method. The claim that at least one active hydrogen group-containing compound (H) contains 50% by mass or more of an active hydrogen group-containing compound (HY-L) having a degree of branching of more than 0.6 as measured by GPC-MALS. 3. The adhesive according to 1 or 2. One or more active hydrogen group-containing compounds (H) contain 70% by mass or more and less than 100% by mass of active hydrogen group-containing compounds (HY) having a branching degree of more than 0.5 as measured by GPC-MALS, The adhesive according to any one of claims 1 to 3, comprising more than 0% by mass and less than 30% by mass of an active hydrogen group-containing compound (HX) having a branching degree of 0.5 or less as measured by the GPC-MALS method. agent. The adhesive according to any one of claims 1 to 4, further comprising a plasticizer. The pressure-sensitive adhesive according to any one of claims 1 to 5, further comprising an antistatic agent. Furthermore, the adhesive according to any one of claims 1 to 6, comprising one or more anti-deterioration agents selected from the group consisting of antioxidants, anti-hydrolysis agents, ultraviolet absorbers, and light stabilizers. agent. A pressure-sensitive adhesive sheet comprising a base sheet and a pressure-sensitive adhesive layer comprising a cured product of the pressure-sensitive adhesive according to any one of claims 1 to 7.

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